Heat exchanger for residential hvac applications

ABSTRACT

A heat exchanger is provided including a first header, a second header, and a plurality of heat exchange tubes arranged in a spaced parallel relationship and fluidly coupling the first and second headers. At least one of the first header, second header and the plurality of heat exchange tubes includes a bend. The heat exchanger having an aspect ratio between about 2 and 6 after formation of the bend.

BACKGROUND

This disclosure relates generally to heat exchangers and, moreparticularly, to a heat exchanger configured for use as an outdoor heatexchanger in residential air conditioning and heat pump applications.

In recent years, much interest and design effort has been focused on theefficient operation of heat exchangers of refrigerant systems,particularly condensers and evaporators. A relatively recent advancementin heat exchanger technology includes the development and application ofparallel flow (such as microchannel, minichannel, brazed-plate,plate-fin, or plate-and frame) heat exchangers as condensers andevaporators.

SUMMARY

According to a first embodiment, a heat exchanger is provided includinga first header, a second header, and a plurality of heat exchange tubesarranged in a spaced parallel relationship and fluidly coupling thefirst and second headers. At least one of the first header, secondheader and the plurality of heat exchange tubes includes a bend. Theheat exchanger having an aspect ratio between about 2 and 6 afterformation of the bend.

In addition to one or more of the features described above, or as analternative, in further embodiments the plurality of heat exchange tubeshave a tube depth between about 8 mm and about 20 mm.

In addition to one or more of the features described above, or as analternative, in further embodiments when the heat exchanger isconfigured for use in a refrigerant system having a capacity less thanthree tons, the depth of the plurality of heat exchange tubes is about10 mm.

In addition to one or more of the features described above, or as analternative, in further embodiments when the heat exchanger isconfigured for use in an refrigerant system having a capacity less thanthree tons, the depth of the plurality of heat exchange tubes is about12 mm.

In addition to one or more of the features described above, or as analternative, in further embodiments when the heat exchanger isconfigured for use in a refrigerant system having a capacity of at leastthree tons, the depth of the plurality of heat exchange tubes is about16 mm.

In addition to one or more of the features described above, or as analternative, in further embodiments the plurality of heat exchange tubeshave a height of about 1.3 mm±0.3 mm.

In addition to one or more of the features described above, or as analternative, in further embodiments the plurality of heat exchange tubeshave a tube pitch between about 8.9 mm and about 15.5. mm.

In addition to one or more of the features described above, or as analternative, in further embodiments the plurality of heat exchange tubeshave a tube pitch of about 9.3 mm.

In addition to one or more of the features described above, or as analternative, in further embodiments the heat exchanger is configured foruse in an air conditioning system.

In addition to one or more of the features described above, or as analternative, in further embodiments the first header and the secondheader are oriented generally vertically and the plurality of heatexchange tubes extend generally horizontally and include the at leastone bend.

In addition to one or more of the features described above, or as analternative, in further embodiments the plurality of heat exchange tubesare bent to form a C or U-shape.

In addition to one or more of the features described above, or as analternative, in further embodiments the heat exchanger is configuredwith a first pass and a second pass. A first portion of the plurality ofheat exchange tubes is configured for the first pass, and a secondportion of the plurality of heat exchange tubes is configured for thesecond pass. A ratio of a number of heat exchange tubes within the firstportion and the second portion is about 2.5 to 6.

In addition to one or more of the features described above, or as analternative, in further embodiments the heat exchanger is configured foruse in a heat pump system.

In addition to one or more of the features described above, or as analternative, in further embodiments the first header and the secondheader are oriented generally horizontally and include the at least onebend, the plurality of heat exchange tubes extend generally verticallythere between.

In addition to one or more of the features described above, or as analternative, in further embodiments the first header and the secondheader are bent to form a C or U-shape.

In addition to one or more of the features described above, or as analternative, in further embodiments the heat exchanger is configuredwith a first pass and a second pass. A first portion of the plurality ofheat exchange tubes is configured for the first pass, and a secondportion of the plurality of heat exchange tubes is configured for thesecond pass. A ratio of a number of heat exchange tubes within the firstportion and the second portion is about 0.3 to about 3.

In addition to one or more of the features described above, or as analternative, in further embodiments a plurality of fins is disposed inthermal communication with the plurality of heat exchange tubes.

In addition to one or more of the features described above, or as analternative, in further embodiments the plurality of fins have a louverlength between about 80% and 90% of a fin height.

In addition to one or more of the features described above, or as analternative, in further embodiments the plurality of fins have a louverpitch between about 1 mm and 1.7 mm.

In addition to one or more of the features described above, or as analternative, in further embodiments wherein the plurality of fins have alouver angle between about 28 degrees and about 45 degrees.

In addition to one or more of the features described above, or as analternative, in further embodiments when the heat exchanger isconfigured for use in an air conditioning system, the plurality of finshave a louver angle of about 32 degrees.

In addition to one or more of the features described above, or as analternative, in further embodiments when the heat exchanger isconfigured for use in a heat pump system, the plurality of fins have alouver angle of about 43 degrees.

In addition to one or more of the features described above, or as analternative, in further embodiments the plurality of fins have a findensity between about 10 fins per inch and about 25 fins per inch.

In addition to one or more of the features described above, or as analternative, in further embodiments the plurality of fins have a finthickness between about 0.07 mm and about 0.1 mm.

In addition to one or more of the features described above, or as analternative, in further embodiments the heat exchanger is configured foruse in an air conditioning system, the plurality of fins have a findensity of 23 fins per inch.

In addition to one or more of the features described above, or as analternative, in further embodiments when the heat exchanger isconfigured for use in a heat pump system, the plurality of fins have afin density of 16 fins per inch.

In addition to one or more of the features described above, or as analternative, in further embodiments one of the first header and secondheader includes the bend and the bend further comprises a ratio of bendradius divided by a total thickness of the heat exchanger. The ratio ofthe bend radius to the total thickness of the heat exchanger is greaterthan 4.

In addition to one or more of the features described above, or as analternative, in further embodiments the plurality of heat exchange tubesincludes the bend and the bend further comprises a ratio of bend radiusdivided by a total thickness of the heat exchanger. The ratio of thebend radius to the total thickness of the heat exchanger is greater than10.

In addition to one or more of the features described above, or as analternative, in further embodiments, the heat exchanger is part of anair management system. The air management system is in fluidcommunication with the heat exchanger and is configured to impart anairflow having an average face velocity of greater than or equal to 200feet per minute over an outer surface of the heat exchanger when thesystem is operating.

In addition to one or more of the features described above, or as analternative, in further embodiments the air management system comprisesa fan.

In addition to one or more of the features described above, or as analternative, in further embodiments a noise level of the system at ameasurement distance of 1 meter from the system is less than or equal to65 dBa.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter, which is regarded as the present disclosure, isparticularly pointed out and distinctly claimed in the claims at theconclusion of the specification. The foregoing and other features, andadvantages of the present disclosure are apparent from the followingdetailed description taken in conjunction with the accompanying drawingsin which:

FIG. 1 is an example of a conventional heat exchanger;

FIG. 2 is a perspective, partly sectioned view of an example of aparallel flow heat exchanger;

FIG. 3 is a cross-sectional view of a portion of the parallel flow heatexchanger of FIG. 2;

FIG. 4 is a perspective view of a heat exchanger configured for use inan air conditioning system according to an embodiment;

FIG. 5 is a perspective view of a heat exchanger configured for use in aheat pump system according to an embodiment; and

FIG. 6 is a schematic diagram of various configurations of a heatexchanger having multiple heat exchanger slabs according to anembodiment.

The detailed description explains embodiments of the present disclosure,together with advantages and features, by way of example with referenceto the drawings.

DETAILED DESCRIPTION

Microchannel heat exchangers as outdoor coils entered residentialcooling only air conditioning applications and are being considered forthe residential heat pump applications as well. Due to regulatoryefficiency requirements, sound constraints, and a non-optimized heatexchanger design, the size of the outdoor heat exchanger is typicallylarge. As a result, the heat pump and air conditioning systems incurhigher costs and have a higher refrigerant charge. Current legislationlimits the amount of charge of refrigerant systems, and heat exchangersin particular, containing most low global warming potential refrigerants(currently classified as A2L substances).

Microchannel heat exchangers have a small internal volume and thereforestore less refrigerant charge than conventional round tube plate finheat exchangers. Although a lower refrigerant charge is generallybeneficial, the smaller internal volume of microchannel heat exchangersmakes them extremely sensitive to overcharge or undercharge situations,which could result in refrigerant charge imbalance, degrade refrigerantsystem performance, and cause nuisance shutdowns. In addition, therefrigerant charge contained in the manifolds of the microchannel heatexchanger, particularly when the heat exchanger operates as a condenser,is significant, such as about half of the total heat exchanger charge.As a result, the refrigerant charge reduction potential of the heatexchanger is limited.

Referring now to FIG. 1, an example of a known parallel flow,microchannel heat exchanger is illustrated. The heat exchanger 20includes a first manifold or header 30, a second manifold or header 40spaced apart from the first manifold 30, and a plurality of heatexchange tubes 50 extending in a spaced parallel relationship betweenand fluidly connecting the first manifold 30 and the second manifold 40.In the illustrated, non-limiting embodiments, the first header 30 andthe second header 40 are oriented generally horizontally and the heatexchange tubes 50 extend generally vertically between the two headers30, 40. By arranging the tubes 50 vertically, water condensate collectedon the tubes 50 is more easily drained from the heat exchanger 30. Inthe non-limiting embodiments illustrated in the FIGS., the headers 30,40 comprise hollow, closed end cylinders having a circularcross-section. However, headers 30, 40 having other configurations, suchas a semi-elliptical, square, rectangular, hexagonal, octagonal, orother cross-sections for example, are within the scope of thedisclosure. The heat exchanger 20 may be used as either a condenser oran evaporator in a vapor compression system, such as a heat pump forexample.

Referring now to FIGS. 2 and 3, each heat exchange tube 50 comprises aflattened heat exchange tube having a leading edge 52, a trailing edge54, a first surface 56, and a second surface 58. The leading edge 52 ofeach heat exchanger tube 50 is upstream of its respective trailing edge52 with respect to an airflow A through the heat exchanger 20. Theinterior flow passage of each heat exchange tube 50 may be divided byinterior walls into a plurality of discrete flow channels 60 that extendover the length of the tubes 50 from an inlet end 62 to an outlet end 64and establish fluid communication between the respective first andsecond manifolds 30, 40. The flow channels 60 may have a circularcross-section, a rectangular cross-section, a trapezoidal cross-section,a triangular cross-section, or another non-circular cross-section (e.g.elliptical, star shaped, closed polygon having straight or curvedsides). The heat exchange tubes 50 including the discrete flow channels60 may be formed using known techniques and materials, including, butnot limited to, extrusion or folding.

As known, a plurality of heat transfer fins 70 (FIG. 3) may be disposedbetween and rigidly attached, usually by a furnace braze process, to theheat exchange tubes 50, in order to enhance external heat transfer andprovide structural rigidity to the heat exchanger 20. Each folded fin 70is formed from a plurality of connected strips or a single continuousstrip of fin material tightly folded in a ribbon-like serpentine fashionthereby providing a plurality of closely spaced fins 72 that extendgenerally orthogonal to the flattened heat exchange tubes 50. Heatexchange between the fluid within the heat exchanger tubes 50 and theair flow A, occurs through the outside surfaces 56, 58 of the heatexchange tubes 50 collectively forming the primary heat exchangesurface, and also through the heat exchange surface of the fins 72 ofthe folded fin 70, which form the secondary heat exchange surface.

Referring again to FIG. 1, the illustrated heat exchanger 20 has asingle-pass flow configuration. For example, refrigerant is configuredto flow from the first header 30 to the second header through theplurality of heat exchanger tubes 50 in the direction indicated by arrowB.

Due to the vertical orientation of the heat exchange tubes 50 inevaporator or heat pump applications, configurations of a parallel flowheat exchanger 20 having a multi-pass flow orientation have not beenfeasible due to refrigerant maldistribution, which is particularlychallenging at high vapor qualities, such as in the intermediatemanifolds for example. With reference now to FIGS. 4 and 5, variousembodiments of an optimized microchannel heat exchanger 20 having amulti-pass configuration are illustrated. Although the heat exchanger 20is illustrated and described herein with reference to a plurality ofmicrochannel tubes 50, embodiments including other types of tubes orconduits connecting the headers 30, 40 are also within the scope of thedisclosure.

To form a multi-pass flow configuration, at least one of the firstmanifold 30 and the second manifold 40 includes two or more fluidlydistinct sections or chambers. In an embodiment, the fluidly distinctsections are formed by coupling separate manifolds together to form thefirst or second manifold 30, 40. Alternatively, a baffle or dividerplate (not shown) known to a person of ordinary skill in the art may bearranged within at least one of the first header 30 and the secondheader 40 to define a plurality of fluidly distinct sections therein.

With reference now to FIG. 4, a heat exchanger 20 configured for use inan air conditioning system (typically as a condenser) is illustrated inmore detail. As shown, the first header 30 and the second header 40 arearranged substantially vertically such that the plurality of heatexchange tubes 50 extends horizontally there between. The plurality ofheat exchanger tubes 50 includes at least one bend. In the illustrated,non-limiting embodiment, the heat exchange tubes 50 form a substantial Cor U-shape between the headers 30, 40. However, heat exchanger tubes 50having any number of bends, such as to form an L, V, W, or S-shape forexample, are also within the scope of the disclosure.

As shown in FIG. 4, the heat exchanger 20 has a two-pass configuration,with each of the first header 30 and second header 40 being divided intoa first section and a second section. When the heat exchanger 20 isconfigured as a condenser, a gaseous refrigerant is provided to a firstsection 30 a of the first header 30 via an inlet 80. From the firstsection 30 a, the refrigerant flows through a first group 50 a of heatexchange tubes 50 to the first section 40 a of the second header 40. Therefrigerant then passes into the second section 40 b of the secondheader 40, through the second group 50 b of heat exchange tubes 50, andinto the second section 30 b of the first header 30. Refrigerant withinthe second section 30 b of the first header 30 may be provided to adownstream component of the system via an outlet 82. As the refrigerantflows sequentially through the first and second groups 50 a, 50 b ofheat exchanger tubes 50, heat from the refrigerant is transferred to anadjacent flow of air A. As a result, a substantially liquid refrigerantis provided at the outlet 82. It should be understood that a heatexchanger having two passes illustrated and described herein is intendedas an example only, and that a heat exchanger having any number ofpasses is also within the scope of the disclosure. For example, thenumber of passes of the heat exchanger 20 may be selected between 1 and4 depending on the system capacity, refrigerant charge, andthermodynamic efficiency.

The heat exchanger 20 is generally optimized to minimize size and costwhile similarly reducing refrigerant charge for a variety of airmanagement systems and airflow configurations. Regardless of the passconfiguration, the heat exchanger 20 may have a face area between about30% and about 60% of a baseline round tube plate fin heat exchanger. Inaddition, an air management system including a fan is configured to moveair over an outer surface of the heat exchanger 20 with a face velocityof up to three times that of a baseline conventional propeller fan. Forexample, when the air management system is configured as an airconditioning system, the minimum face velocity is about 270 ft/min andwhen the air management system is configured as a heat pump system theminimum face velocity is about 220 ft/min. The heat exchanger 20 mayalso be configured such that a ratio of the heat exchange tubes 50 a inthe first pass to the heat exchange tubes 50 b in the second pass isabout 2.5 to 6. In another embodiment, a ratio of the length of the heatexchanger 20 to the height of the heat exchanger 20 measured in a planecoinciding with the face area of the heat exchanger 20 (e.g. a planeperpendicular to the dimension along which the tube depth is measured)when folded in the bent configuration, also referred to as the aspectratio, is between about 2 and 6.

With reference now to FIG. 5, a heat exchanger 20 configured for use ina heat pump system also has a shape including at least one bend. Forexample, the illustrated heat exchanger 20 has a C or U-shape similar tothe heat exchanger 20 of FIG. 4. However, in this embodiment, the atleast one bend is formed in the first header 30 and the second header40, not the tubes 50. Each of the first header 30 and the second header40 is generally divided into a first, second, and third section,respectively. A first group 50 a of heat exchanger tubes 50 extendsvertically between the first sections 30 a, 40 a of the first and secondheader 30, 40, a second group 50 b of heat exchanger tubes 50 extendsvertically between the second sections 30 b, 40 b of the first andsecond header 30, 40, and a third group 50 c of heat exchanger tubes 50extends vertically between the third sections 30 c, 40 c of the firstand second header 30, 40. In an embodiment, a length of the first andthird sections of the headers 30, 40 and the number of tubes 50 withinthe first and third groups 50 a, 50 c are substantially identical.

Although the heat exchanger 20 of FIG. 5 has a two-pass flowconfiguration, a configuration including any number of passes, forexample between 2 and 5 passes is within the scope of the disclosure.The direction of fluid through the heat exchanger 20 may depend on themode in which the heat pump is being operated. For example, when theheat exchanger 20 is configured to operate as an evaporator and heat thefluid therein, a two-phase refrigerant mixture is provided via an inlet(not shown) to the second section 30 b of the first header 30. Withinthe second section 30 b, the refrigerant is configured to flow throughthe second group 50 b of tubes 50 to the second section 40 b of thesecond header 40. From the second section 40 b of the second header 40,the fluid flow is configured to divide such that a portion of the fluidflows into the first section 40 a of the second header 40 and a portionof the fluid flows into the third section 40 c of the second header 40,and through the first and third groups of tubes 50 a, 50 c,simultaneously. Once received within the first section 30 a of the firstheader 30 and the third section 30 c of the first header 30, the fluidis provided via outlets 80 to a conduit (not shown) where the fluid isrejoined and provided to a downstream component of a vapor compressionsystem.

As the refrigerant flows sequentially through the second and firstgroups 50 b, 50 a of heat exchanger tubes 50, or alternatively, throughthe second and third groups 50 b, 50 c of heat exchanger tubes 50, heatfrom an adjacent flow of air A, is transferred to the refrigerant. As aresult, a substantially vaporized refrigerant is provided at the outlets80. Alternatively, refrigerant is configured to flow in a reversedirection through the heat exchanger 20 when operated as a condenser.

The face area of the heat exchanger 20 configured for use in a heat pumpis between about 30% and about 70% of the baseline round tube plate finheat exchanger with a higher face velocity of up to three times abaseline conventional propeller fan. This increased face velocity occursas a result of the combination of increased air flow and the smallerface area of the heat exchanger 20. In addition, the noise generated bythe heat exchanger 20 may be reduced compared to conventional heatexchangers. As a result, the noise of a system containing by the heatexchanger 20 is at or below an allowable noise level for residentialapplications. For example, the noise level of a refrigerant systemmeasured at a distance of 1 meter from the system is less than or equalto 65 dBa.

The heat exchanger 20 may also be configured such that when operated asa condenser, a ratio of the heat exchange tubes 50 in the first pass (50a and 50 c) to the second pass (50 b) is about 0.3 to 3. In anotherembodiment, the aspect ratio of the heat exchanger 20 is between about 2and 6.

To further optimize the heat exchanger 20, for example a heat exchanger20 configured for use in any heat transfer application and having anytube depth, the size of the headers 30, 40 may be reduced, such that theheaders 30, 40 have an inner diameter equal to a width of one of theheat exchange tubes 50 plus 1-4 mm (millimeters). In addition, the tubes50 of the heat exchangers 20 may have a depth between about 8 mm and 16mm, and in an embodiment between about 10 to 12 mm, or 10 mm. Further,in embodiments where the heat exchanger 20 is configured for use in asystem having a capacity between about three tons and five tons, thetubes 50 may have a depth between about 12 mm and 22 mm, morespecifically 14 to 16 mm. In another embodiment, the tubes 50 may have aheight of about 1.3 mm±0.3 mm The tubes of the heat exchanger 20 mayadditionally have a tube pitch between about 8.9 mm and 15.5 mm, e.g.,9.3 mm.

With respect to the fins 70, the fins 70 mounted to each of theplurality of tubes 50 may have a louver length between about 80%-90% ofthe fin height, a louver pitch between about 0.8 mm and 1.7 mm, e.g.,1.3 mm, and a louver angle between 28 degrees and 47 degrees. In anembodiment, the louver angle of the fins 70 in a heat exchanger 20configured for use in an air conditioning system is about 30 degrees andthe louver angle in a heat exchanger configured for use in a heat pumpis about 45 degrees. The fin density in a heat exchanger 20 for use inan air conditioning system may be between about 18-25 fins/inch, e.g.,23 fins per inch. Alternatively, the fin density of a heat exchanger 20configured for use in a heat pump may be between about 12-18 fins/inch,e.g., about 16 fins per inch.

The heat exchangers 20 provided herein result in a substantial size andtherefore cost reduction, between 30 and 70% compared to other heatexchangers.

Further, this reduced size can allow for refrigerant charge of thesystem to be reduced from 50-70% compared to the baseline heatexchanger. The heat exchangers 20 additionally have a higher performancedue to improvements in both refrigerant and air distribution, along withthe optimal heat transfer and hydraulic resistance balance by optimizingthe number of refrigerant passes and airflow.

In an embodiment, the heat exchanger 20 has a multi-slab configurationsuch that the heat exchanger 20 includes at least a first slab 80 and asecond, substantially identical slab 82 arranged downstream from thefirst slab 80 relative to an airflow A. In an embodiment, the pluralityof heat exchange tubes 50, or alternatively, the headers 30, 40 includeat least one bend to form the first heat exchanger slab 80 and thesecond heat exchanger slab 82. However, in alternate embodiments, thefirst slab 80 and the second slab 82 may be distinct. Variousconfigurations of a heat exchanger 20 having a first and second heatexchanger slab 80, 82 are illustrated in FIG. 6. It should be understoodthat embodiments including more than two heat exchanger slabs are alsowithin the scope of the disclosure.

A total thickness of the heat exchanger 20 is measured between anexterior surface of a first heat exchanger slab and an exterior surfaceof the furthest heat exchanger slab of the heat exchanger 20. Inembodiments where the plurality of tubes 50 are bent, the ratio of thebend radius (measured to a centerline of the heat exchanger 20) to thetotal thickness of the heat exchanger 20 at the bend is greater than 10,and in an embodiment is equal to about 15±4. In embodiments where theheaders 30, 40 of the heat exchanger 20 are bent to define a pluralityof heat exchanger slabs, the ratio of the bend radius to the totalthickness of the heat exchanger at the bend is greater than 4, and in anembodiment is equal to about 7±2.5. In addition, when the header 30, 40is bent about 180 degrees, a spacer may be positioned on opposing sidesof the bend to prevent the adjacent portions from contacting oneanother. By forming the one or more bends of the heat exchanger tubes 50or the headers 30, 40 with a minimum bend radius, the formation of sharpbends that may constrict the flow of a fluid there through areeliminated.

Embodiment 1

A heat exchanger, comprising a first header; a second header; aplurality of heat exchange tubes arranged in spaced parallelrelationship and fluidly coupling the first header and second header;wherein one of the first header, second header and the plurality of heatexchange tubes include a bend, the heat exchanger having an aspect ratiobetween 2 and 6 after formation of the bend.

Embodiment 2

The heat exchanger according to an embodiment, wherein the plurality ofheat exchange tubes have a tube depth between about 8 mm and about 20mm.

Embodiment 3

The heat exchanger according to embodiment 2, wherein when the heatexchanger is configured for use in a refrigerant system having acapacity less than three tons, the depth of the plurality of heatexchange tubes is about 10 mm.

Embodiment 4

The heat exchanger according to embodiment 2, wherein when the heatexchanger is configured for use in an refrigerant system having acapacity less than three tons, the depth of the plurality of heatexchange tubes is about 12 mm.

Embodiment 5

The heat exchanger according to embodiment 2, wherein when the heatexchanger is configured for use in a refrigerant system having acapacity of at least three tons, the depth of the plurality of heatexchange tubes is about 16 mm.

Embodiment 6

The heat exchanger according to any of the preceding embodiments,wherein the plurality of heat exchange tubes have a height of about 1.3mm±0.3 mm.

Embodiment 7

The heat exchanger according to any of the preceding embodiments,wherein the plurality of heat exchange tubes have a tube pitch betweenabout 8.9 mm and about 15.5. mm.

Embodiment 8

The heat exchanger according to claim 7, wherein the plurality of heatexchange tubes have a tube pitch of about 9.3 mm.

Embodiment 9

The heat exchanger according to any of the preceding embodiments,wherein the heat exchanger is configured for use in an air conditioningsystem.

Embodiment 10

The heat exchanger according to embodiment 9, wherein the first headerand the second header are oriented generally vertically and theplurality of heat exchange tubes extend generally horizontally andinclude the at least one bend.

Embodiment 11

The heat exchanger according to embodiment 10, wherein the plurality ofheat exchange tubes are bent to form a C or U-shape.

Embodiment 12

The heat exchanger according to any of embodiments 9-11, wherein theheat exchanger is configured with a first pass and a second pass, afirst portion of the plurality of heat exchange tubes being configuredfor the first pass, and a second portion of the plurality of heatexchange tubes being configured for the second pass, wherein a ratio ofa number of heat exchange tubes within the first portion and the secondportion is about 2.5 to 6.

Embodiment 13

The heat exchanger according to any of the preceding embodiments,wherein the heat exchanger is configured for use in a heat pump system.

Embodiment 14

The heat exchanger according to embodiment 13, wherein the first headerand the second header are oriented generally horizontally and includethe at least one bend, the plurality of heat exchange tubes extendgenerally vertically there between.

Embodiment 15

The heat exchanger according to embodiment 14, wherein the first headerand the second header are bent to form a C or U-shape.

Embodiment 16

The heat exchanger according to any of embodiment 13-15, wherein theheat exchanger is configured with a first pass and a second pass, afirst portion of the plurality of heat exchange tubes being configuredfor the first pass, and a second portion of the plurality of heatexchange tubes being configured for the second pass, wherein a ratio ofa number of heat exchange tubes within the first portion and the secondportion is about 0.3 to about 3.

Embodiment 17

The heat exchanger according to any of the preceding embodiments,wherein a plurality of fins is disposed in thermal communication withthe plurality of heat exchange tubes.

Embodiment 18

The heat exchanger according to embodiment 17, wherein the plurality offins have a louver length between about 80% and 90% of a fin height.

Embodiment 19

The heat exchanger according to any of embodiments 17-18, wherein theplurality of fins have a louver pitch between about 1 mm and 1.7 mm.

Embodiment 20

The heat exchanger according to any of embodiments 17-19, wherein theplurality of fins have a louver angle between about 28 degrees and about45 degrees.

Embodiment 21

The heat exchanger according to embodiment 20, wherein when the heatexchanger is configured for use in an air conditioning system, theplurality of fins have a louver angle of about 32 degrees.

Embodiment 22

The heat exchanger according to embodiment 20, wherein when the heatexchanger is configured for use in a heat pump system, the plurality offins have a louver angle of about 43 degrees.

Embodiment 23

The heat exchanger according to any of embodiments 17-22, wherein theplurality of fins have a fin density between about 10 fins per inch andabout 25 fins per inch.

Embodiment 24

The heat exchanger according to any of embodiments 17-23, wherein theplurality of fins have a fin thickness between about 0.07 mm and about0.1 mm.

Embodiment 25

The heat exchanger according to embodiment 24, wherein when the heatexchanger is configured for use in an air conditioning system, theplurality of fins have a fin density of 23 fins per inch.

Embodiment 26

The heat exchanger according to embodiment 24, wherein when the heatexchanger is configured for use in a heat pump system, the plurality offins have a fin density of 16 fins per inch.

Embodiment 27

The heat exchanger of any of the preceding embodiments, wherein one ofthe first header and second header includes the bend and the bendfurther comprises a ratio of bend radius divided by a total thickness ofthe heat exchanger, wherein the ratio is greater than 4.

Embodiment 28

The heat exchanger of any of claims the preceding embodiments, whereinthe plurality of heat exchange tubes includes the bend and the bendfurther comprises a ratio of bend radius divided by a total thickness ofthe heat exchanger, wherein the ratio is greater than 10.

Embodiment 29

A system comprising: the heat exchanger according to any of thepreceding embodiments; and an air management system in fluidcommunication with the heat exchanger and configured to impart on anairflow having an average face velocity of greater than or equal to 200feet per minute over an outer surface of the heat exchanger when thesystem is operating.

Embodiment 30

The system of embodiment 29, wherein the air management system comprisesa fan.

Embodiment 31

The system of any of embodiments 29-30, a noise level of the system at ameasurement distance of 1 meter from the system is less than or equal to65 dBa.

While the present disclosure has been particularly shown and describedwith reference to the exemplary embodiments as illustrated in thedrawing, it will be recognized by those skilled in the art that variousmodifications may be made without departing from the spirit and scope ofthe present disclosure. Therefore, it is intended that the presentdisclosure not be limited to the particular embodiment(s) disclosed as,but that the disclosure will include all embodiments falling within thescope of the appended claims.

1. A heat exchanger, comprising: a first header; a second header; aplurality of heat exchange tubes arranged in spaced parallelrelationship and fluidly coupling the first header and second header;wherein one of the first header, second header and the plurality of heatexchange tubes include a bend, the heat exchanger having an aspect ratiobetween 2 and 6 after formation of the bend.
 2. The heat exchangeraccording to claim 1, wherein the plurality of heat exchange tubes havea tube depth between about 8 mm and about 20 mm.
 3. The heat exchangeraccording to claim 2, wherein when the heat exchanger is configured foruse in a refrigerant system having a capacity less than three tons, thedepth of the plurality of heat exchange tubes is about 10 mm.
 4. Theheat exchanger according to claim 2, wherein when the heat exchanger isconfigured for use in an refrigerant system having a capacity less thanthree tons, the depth of the plurality of heat exchange tubes is about12 mm.
 5. The heat exchanger according to claim 2, wherein when the heatexchanger is configured for use in a refrigerant system having acapacity of at least three tons, the depth of the plurality of heatexchange tubes is about 16 mm.
 6. The heat exchanger according to claim1, wherein the plurality of heat exchange tubes have a height of about1.3 mm±0.3 mm.
 7. The heat exchanger according to claim 1, wherein theplurality of heat exchange tubes have a tube pitch between about 8.9 mmand about 15.5. mm.
 8. The heat exchanger according to claim 7, whereinthe plurality of heat exchange tubes have a tube pitch of about 9.3 mm.9. The heat exchanger according to claim 1, wherein the heat exchangeris configured for use in an air conditioning system.
 10. (canceled) 11.(canceled)
 12. The heat exchanger according to claim 9, wherein the heatexchanger is configured with a first pass and a second pass, a firstportion of the plurality of heat exchange tubes being configured for thefirst pass, and a second portion of the plurality of heat exchange tubesbeing configured for the second pass, wherein a ratio of a number ofheat exchange tubes within the first portion and the second portion isabout 2.5 to
 6. 13. The heat exchanger according to claim 1, wherein theheat exchanger is configured for use in a heat pump system. 14.(canceled)
 15. (canceled)
 16. (canceled)
 17. The heat exchangeraccording to claim 1, wherein a plurality of fins is disposed in thermalcommunication with the plurality of heat exchange tubes.
 18. The heatexchanger according to claim 17, wherein the plurality of fins have alouver length between about 80% and 90% of a fin height.
 19. The heatexchanger according to claim 12, wherein the plurality of fins have alouver pitch between about 1 mm and 1.7 mm.
 20. The heat exchangeraccording to claim 12, wherein the plurality of fins have a louver anglebetween about 28 degrees and about 45 degrees. 21-26. (canceled)
 27. Theheat exchanger of claim 1, wherein one of the first header and secondheader includes the bend and the bend further comprises a ratio of bendradius divided by a total thickness of the heat exchanger, wherein theratio is greater than
 4. 28. The heat exchanger of claim 1, wherein theplurality of heat exchange tubes includes the bend and the bend furthercomprises a ratio of bend radius divided by a total thickness of theheat exchanger, wherein the ratio is greater than
 10. 29. A systemcomprising: the heat exchanger according to any of the preceding claims;and an air management system in fluid communication with the heatexchanger and configured to impart on an airflow having an average facevelocity of greater than or equal to 200 feet per minute over an outersurface of the heat exchanger when the system is operating.
 30. Thesystem of claim 18, wherein the air management system comprises a fan.31. The system of claim 18, a noise level of the system at a measurementdistance of 1 meter from the system is less than or equal to 65 dBa.